There has been some discussion of a brightening of Edom Promontorium this apparition; brightenings which are remiscent of such events from Japanese observers in the past. The following is a series of e-mail alerts I received, including some predictions for others to try to view them. The messages are presented for the most part as I received them (I converted them to HTML format for better presentation and made a correction to one message based on an errata follow-up). —Dave
I am pleased to report that after two uneventful nights of observing our team here in the Florida Keys detected significant brightness fluctuations over Edom between 06:40 and 07:30 UT on 7 June, 2001 UTD. Our observing team consisted of Tippy and Patty D'Auria; David Moore; Rick Fienberg, Tom Dobbins, and Gary Seronik of Sky and Telescope Magazine, and me. Instruments included two six-inch Newtonian reflectors and a Meade 12-inch SCT used in conjunction with a monochrome video camera.
A perceptible brightening of Edom was noted around 06:35 UT. By 06:40 UT pronounced pulsations in brightness were evident. These events occurred at roughly 10 to15 second intervals, with brightness maxima of approximately 3 seconds duration that could not be attributed to atmospheric turbulence. These dramatic variations in brightness were simultaneously detected by visual observers at the eyepieces of the 6-inch Newtonians and by those viewing the video monitor. It is notable that they could not be seen with an 85mm refractor.
Further details and images extracted from the videotape will be forthcoming in the near future. Meanwhile, I would be grateful if you would alert other observers to the possibility of repeating these observations, as calculations suggest that the optimum Sun-Earth-Mars geometry for specular reflections at Edom will occur on 8 June UT.
Best regards,
Don
We again observed Mars from the Florida Keys this morning (8 June 2001 UTD) from 05:40 UT to 08:36 UT. There appeared to be two peaks in brightening phenomena around Edom. The first was a series of short-lived (3-5 second) brightenings observed both visually and via video between 07:00 and 07:20 UT. Mars' altitude was 35 degrees. These were quite pronounced and were similar in frequency to those of 7 June. The second group of events occurred between 07:53 and 08:24 UT (altitude = 26 degs), when a series of small but frequent brightness variations were detected.
In general, the events of this morning displayed the same intensity but less frequency than those of 7 June.
Observers included Dan Troiani, Tippy D'Auria, Scott and Lou Ireland, Carolyn and Mark Peterson, Bob Itzenthaler, and Don Parker. Instruments were a 6-inch f/8 Newtonian for continuous visual observation from 05:51-08:36 UT and a 12-inch Meade SCT used in conjunction with a monochrome video camera, taping from 05:51-08:36 UT.
Observational conditions were very favorable, with light ESE wind and high cirrus. Seeing was 8 initially, deteriorating to 4-5 as the planet's altitude fell below 30 degrees. Clouds interfered with observations less than 20% of the time.
We will attempt to make further observations tomorrow morning (9 June UTD), but the areas of interest will not be favorably presented until Mars' altitude is less than 30 degrees.
Best,
Don
I also saw no Edom unusual brightening during the period 07:00 to 09:30 UT in intermittent visual monitoring with a 10-inch (25-cm) Newtonian at 300X from Lincoln, Nebraska, USA. I had intensive monitoring between 07:33 and 07:53 UT when the seeing was often quite good. After 07:53 clouds allowed only a few breaks for viewing, but the seeing was exceptionally good. By 09:30 Mars was low and the seeing was very poor.
Martin Gaskell
Dept. Physics & Astronomy
Univ. Nebraska
The inspiring article by Thomas Dobbins and William Sheehan in the May issue of Sky & Telescope is wonderfully researched and well written. However there are some problems in the predictions that might mislead observers into being much too restrictive when they look for brightness fluctuations. The good news is that the best time is still to come. As in 1954, it will be in July, not early June.
Assuming that reflecting ice crystals are suspended horizontally, the condition for specular reflection around local noon when Mars is in opposition is that the latitude of the reflecting region equals the mean of the declination of the sun (D(S)) and the declination of the earth (D(e)). Although this is stated correctly on p. 122 of T. Dobbins & W. Sheehan (2001, Sky & Telescope, 101, 115), their table on p. 123 is instead for the condition D(S) = D(e) around opposition. The mean of the declinations of the earth and sun in this table are +2 degrees while the crater Schiaparelli in Edom Promontorium lies at a latitude of -2 degrees. The specular reflection conditions will actually be met most closely at end of July, one half of the phase angle after each central meridian transit.
The sudden 1953 July 24 Edom brightening did not take place under ideal conditions for specular reflection since the right ascensions of the earth and sun were wrong for the reported time of observation. The historical observations and the recent observations of brightness fluctuations more than an hour away from the Dobbins & Sheehan predicted times show that brightenings are possible over a wide range of dates and times. Conditions for specular reflection comparable to those of the last few days will persist until the end of August. Observers are urged to continue monitoring for brightness fluctuations until this time.
I urge anyone who doesn't understand this to draw diagrams, run planetarium programs, and try to think it through.
Incidentally, the bright spot people see out of aircraft windows below the aircraft is usually the narrow backscattering that occurs with small aerosols in clouds, not specular reflection off ice, and I suspect that the picture on p. 122 in S& T might really be of the former.
C. Martin Gaskell
Dept. Physics & Astronomy
University of Nebraska
Lincoln, NE 68588-0111
Here is my best effort at generating ephemerides, based on the following presumptions: Edom Promintorium stretches from -7 to 4° latitude and 345 to 353°longitude. These values are based on Gerard de Vaucouleurs' analysis of Shiro Ebisawa's map (see Gerard de Vaucouleurs "Charting the Martian Surface" S&T, October 1965, pp. 196-201.) According to the Batson, Bridges, Inge "Atlas of Mars" (NASA, 1979), the Schiaparelli crater is centered at 343° longitude, -3° latitude. I have used a value of 345° for Edom Promintorium for calculating the times of possible future events.
It would appear that Japanese observers may yet have an opprtunity to witness these events without leaving their native soil!
Tom Dobbins
I.) LATITUDES
De = Declination of Earth from Mars
Ds = Declination of Sun from Mars
(De + Ds)/2 = Martian latitude of possible specular reflection
July 11 De = 7.0 Ds = -5.7 (De+Ds)/2 = 0.65
July 12 De = 7.0 Ds = -5.9 (De+Ds)/2 = 0.55
July 13 De = 7.1 Ds = -6.2 (De+Ds)/2 = 0.45
July 14 De = 7.1 Ds = -6.4 (De+Ds)/2 = 0.30
July 15 De = 7.2 Ds = -6.7 (De+Ds)/2 = 0.25
July 16 De = 7.2 Ds = -6.9 (De+Ds)/2 = 0.15
July 17 De = 7.2 Ds = -7.1 (De+Ds)/2 = 0.05
July 18 De = 7.2 Ds = -7.4 (De+Ds)/2 = -0.10
July 19 De = 7.2 Ds = -7.6 (De+Ds)/2 = -0.20
July 20 De = 7.2 Ds = -7.8 (De+Ds)/2 = -0.30
July 21 De = 7.2 Ds = -8.1 (De+Ds)/2 = -0.45
July 22 De = 7.2 Ds = -8.3 (De+Ds)/2 = -0.55
July 23 De = 7.2 Ds = -8.5 (De+Ds)/2 = -0.65
July 24 De = 7.2 Ds = -8.8 (De+Ds)/2 = -0.80
July 25 De = 7.1 Ds = -9.0 (De+Ds)/2 = -1.05
July 26 De = 7.1 Ds = -9.3 (De+Ds)/2 = -1.10
July 27 De = 7.0 Ds = -9.5 (De+Ds)/2 = -1.25
July 28 De = 7.0 Ds = -9.7 (De+Ds)/2 = -1.35
July 29 De = 6.9 Ds = -10.0 (De+Ds)/2 = -1.55
July 30 De = 6.8 Ds = -10.2 (De+Ds)/2 = -1.70
July 31 De = 6.7 Ds = -10.5 (De+Ds)/2 = -1.90
Aug 01 De = 6.7 Ds = -10.7 (De+Ds)/2 = -2.00
Aug 02 De = 6.6 Ds = -10.9 (De+Ds)/2 = -2.15
Aug 03 De = 6.5 Ds = -11.0 (De+Ds)/2 = -2.25
Aug 04 De = 6.4 Ds = -11.2 (De+Ds)/2 = -2.40
Aug 05 De = 6.3 Ds = -11.5 (De+Ds)/2 = -2.60
Aug 06 De = 6.2 Ds = -11.7 (De+Ds)/2 = -2.75
Aug 07 De = 6.1 Ds = -11.9 (De+Ds)/2 = -2.90
Aug 08 De = 6.0 Ds = -12.1 (De+Ds)/2 = -3.05
Aug 09 De = 5.9 Ds = -12.4 (De+Ds)/2 = -3.25
Aug 10 De = 5.7 Ds = -12.6 (De+Ds)/2 = -3.45
II.) LONGITUDES & TIMES
Phase i = Planetocentric elongation of Mars with respect to
Earth and Sun in degrees
(Phase i)/2 = Distance in degrees of longitude from CM
(in direction of evening limb post opposition) of
possible specular reflection
Longitude Offset = 345 + (Phase i)/2 = longitude of Martian
CM for specular reflection at Edom Promintorium
Time = Nominal UT time of possible specular reflection at
Edom Promintorium
July 11 Phase i = 22.9 degrees (Phase i)/2 = 11.4 Longitude Offset =356.4 Time = 04:28
July 12 Phase i = 23.6 degrees (Phase i)/2 = 11.8 Longitude Offset =356.8 Time = 05:05
July 13 Phase i = 24.3 degrees (Phase i)/2 = 12.2 Longitude Offset =357.2 Time = 05:46
July 14 Phase i = 24.9 degrees (Phase i)/2 = 12.4 Longitude Offset =357.4 Time = 06:23
July 15 Phase i = 25.6 degrees (Phase i)/2 = 12.8 Longitude Offset =357.8 Time = 07:01
July 16 Phase i = 26.2 degrees (Phase i)/2 = 13.1 Longitude Offset =358.1 Time = 07:42
July 17 Phase i = 26.9 degrees (Phase i)/2 = 13.5 Longitude Offset =358.5 Time = 08:19
July 18 Phase i = 27.5 degrees (Phase i)/2 = 13.8 Longitude Offset =358.8 Time = 08:56
July 19 Phase i = 28.1 degrees (Phase i)/2 = 14.0 Longitude Offset =359.0 Time = 09:38
July 20 Phase i = 28.7 degrees (Phase i)/2 = 14.4 Longitude Offset =359.4 Time = 10:15
July 21 Phase i = 29.3 degrees (Phase i)/2 = 14.6 Longitude Offset =359.6 Time = 10:53
July 22 Phase i = 29.8 degrees (Phase i)/2 = 14.9 Longitude Offset =359.9 Time = 11:30
July 23 Phase i = 30.4 degrees (Phase i)/2 = 15.2 Longitude Offset =000.2 Time = 12:12
July 24 Phase i = 30.9 degrees (Phase i)/2 = 15.5 Longitude Offset =000.5 Time = 12:49
July 25 Phase i = 31.5 degrees (Phase i)/2 = 15.8 Longitude Offset =000.8 Time = 13:27
July 26 Phase i = 32.0 degrees (Phase i)/2 = 16.0 Longitude Offset =001.0 Time = 14:08
July 27 Phase i = 32.5 degrees (Phase i)/2 = 16.3 Longitude Offset =001.3 Time = 14:47
July 28 Phase i = 33.0 degrees (Phase i)/2 = 16.5 Longitude Offset =001.5 Time = 15:25
July 29 Phase i = 33.4 degrees (Phase i)/2 = 16.7 Longitude Offset =001.7 Time = 16:02
July 30 Phase i = 33.9 degrees (Phase i)/2 = 17.0 Longitude Offset =002.0 Time = 16:44
July 31 Phase i = 34.4 degrees (Phase i)/2 = 17.2 Longitude Offset =002.2 Time = 17:23
Aug 01 Phase i = 34.8 degrees (Phase i)/2 = 17.4 Longitude Offset =002.4 Time = 18:01
Aug 02 Phase i = 35.2 degrees (Phase i)/2 = 17.6 Longitude Offset =002.6 Time = 18:42
Aug 03 Phase i = 35.7 degrees (Phase i)/2 = 17.8 Longitude Offset =002.8 Time = 19:21
Aug 04 Phase i = 36.1 degrees (Phase i)/2 = 18.0 Longitude Offset =003.0 Time = 19:59
Aug 05 Phase i = 36.5 degrees (Phase i)/2 = 18.3 Longitude Offset =003.3 Time = 20:37
Aug 06 Phase i = 36.8 degrees (Phase i)/2 = 18.4 Longitude Offset =003.4 Time = 21:16
Aug 07 Phase i = 37.2 degrees (Phase i)/2 = 18.6 Longitude Offset =003.6 Time = 21:57
Aug 08 Phase i = 37.6 degrees (Phase i)/2 = 18.8 Longitude Offset =003.8 Time = 22:33
Aug 09 Phase i = 37.9 degrees (Phase i)/2 = 19.0 Longitude Offset =004.0 Time = 23:14
Aug 10 Phase i = 38.3 degrees (Phase i)/2 = 19.2 Longitude Offset =004.2 Time = 23.53
The anomalous brightenings at Edom Promintorium witnessed from the Florida Keys occured at under the conditions described below...
CM at 6:40 UT was 330°; CM at 7:20 was 342°. This corresponds to sources at longitudes of 333 to 345°, assuming a horizontal, planar reflecting surface.
De = 1.7° Ds = 2.5° Assuming a horizontal reflecting surface, the nominal position of the source of the reflection should be at (1.7 + 2.5)/2 = 2.1°.
CM at 7:00 UT was 326°; CM at 7:20 was 331°. This corresponds to sources at longitudes of 328.5 to 333.5°.
CM at 7:53 UT was 339°; CM at 8:24 was 347°. This corresponds to sources at longitudes of approximately 342 to 349°, assuming a horizontal, planar reflecting surface.
De = 1.9° Ds = 2.2° Assuming a horizontal reflecting surface, the nominal position of the source of the reflection should be at (1.9 + 2.2)/2 = 2.05°.
It is noteworthy that despite a source latitude of 2.1 to 2.5° suggested by the values of De and Ds, the apparent location of the center of the activity appeared to be several degrees to the south.
The recent revised ephemeris is for an idealized horizontal reflector in the Schiaparelli crater. Observers are cautioned that analysis of the recent observations by the Florida Keys observers and of historical observations of sudden Edom brightenings imply that the effective reflecting planes can be inclined at several degrees both in latitude and longitude (note, for example, the long time period during which the June 7 and June 8 flarings were each seen). Observers should therefore start watching up to an hour and a half before the predicted times. Although the revised ephemeris runs only into August, conditions will remain favorable through September, and, fortunately, the apparent size of Mars remains large for a long time this apparition. Flaring before early June was also possible so observations of Edom Promontorium earlier in the apparition are of interest.
Although obviously less exciting for the observer than positive detections, negative reports are also of great value in characterizing the phenomenon.
Martin Gaskell
Dept. Physics & Astronomy
Univ. Nebraska